During the 11-day mission's five spacewalks, astronauts will install two new instruments, repair two inactive ones and perform the component replacements that will keep the telescope functioning into at least 2014.

In addition to the originally scheduled work, Atlantis also will carry a replacement Science Instrument Command and Data Handling Unit for Hubble. Astronauts will install the unit on the telescope, removing the one that stopped working on Sept. 27, 2008, delaying the servicing mission until the replacement was ready. ~ latest space shuttle news from nasa